Terephthalic acid and trimellitic acids comprise a benzene ring with carboxylate groups at the 1,4 and the 1,2,4 positions respectively. These acids and their carboxylate derivatives are useful in a variety of commercial products such as polyesters and plasticizers. At the present time these acids and their carboxylate derivatives are synthesized commercially from petroleum based starting materials, such as p-xylene. Due to volatility in hydrocarbon markets and the limited amount of hydrocarbons available for future use it is desirable that methods of preparing such important compounds from renewable resources be developed.
Some large agricultural crops such as corn and sugar cane and the by-products associated with their harvesting and processing which cannot be used as a food source contain starch or cellulosic materials which can be broken down to simple sugars which can then be converted to useful products. See, for instance, Frost et. al. U.S. Pat. No. 5,629,181; Frost U.S. Pat. No. 5,168,056; Frost et. al. U.S. Pat. No. 5,272,073; Frost U.S. Patent publication 2007/0178571, and Frost et. al. U.S. Pat. No. 5,616,496, incorporated herein by reference.
There is a need for substituted and unsubstituted benzene 1,4-dicarboxylate compounds (terephthalic acid and carboxylate derivatives thereof) and processes for preparing such compounds from starting materials that can be made or derived from renewable resources, such as, for example, biomass or simple sugars which can then be derived from biomass.